Differential drying of resin-impregnated fabric to obtain differential dyeing effects



Patented Feb. 4, 1947 DIFFERENTIAL DRYING F RESIN-IMTREG- NATED FABRICTO OBTAEN DIFFEREN- TEAL DYEING EFFECTS Croyden M. Whittaker, CheadleHulme, Henry A.

Thomas, Hazel Grove, Cliiford C. Wilcock, Sal'- ford, and Charles P.Tattersfield, Audenshaw, near Manchester, England, assignors toCourtaulds Limited, London, England, a British company No Drawing.

Serial No. 519,378. 10, 1943 Claims.

This invention relates to the production of differential dyeing effectson fabrics, in which difierent portions of the fabric are difierentlycolored. The invention can be carried out so that, for instance, oneside of the fabric is colored difierently from those of the other side,or so that different portions of the same side of the fabric aredifferently colored.

We have found that by impregnating a textile fabric with a solution orsuspension of a nonvolatile dyestuff or of resin-forming compounds whichare capable of altering the dyeing prop erties of the fabric, saiddyestuffs and resinforming compounds having no affinity or a lowaffinity, or in other words at the most only a low affinity for thematerial of the fabric, and evaporating the impregnating liquid morerapidly from one portion of the fabric than from another portion, we canobtain dilferential effects on the two portions of the fabric, so that,in the case of a dyestuff, the portions are differently colored and, inthe case of resin-forming compounds, different color effects areobtained on subsequently heating the fabric to effect condensation andthen dyeing. If for instance the impregnating liquor be evaporated morerapidly from one side of the fabric than from the other by blowing air,either hot, warm or cold, onto one side of the fabric only, it will befound that. the two sides are, or can be, differently colored. If it isdesired to produce a differential effect on different portions of oneside of the fabric, then suitable means for localising the evaporationon that side are employed; for instance a stencil or template or othermeans for assisting the production of a local drying can be employed.Thus, if a spun viscose rayon fabric be impregnated with a solutioncontaining cyanamide, formaldehyde and ammonium thiocyanate, and thefabric be then dried by blowing hot air onto one side only, and thedried fabric be then heated to a temperature of about 140 Centigradeuntil the condensation product has been formed, a very markeddifferential effect will be produced, as is shown when the fabric isdyed with a wool dyestuff.

In the treatment of fabrics with a solution containing cyanamide,formaldehyde and ammonium thiocyanate as just described, the ammoniumthiocyanate acts in its known capacity as a catalyst, that is, itgreatly increases the afiinity of the material of the fabric for certaindirect dyestuffs. Other known catalysts may be added to the solution orsuspension of'the resin-forming compounds. 7 r

Application January 22, 1944,

Great Britain March Generally speaking, if the material be squeezed morelightly, so as to leave therein a greater proportion of the impregnatingliquid, more pronounced differential effects will be obtained whencarrying out the drying process according to this invention.

If the impregnating solution has any considerable substantive afiinityfor the material, such for instance as that possessed by certaindyestuffs, the differential dyeing effect, which it is our object toattain, is not produced. For instance, viscose staple fibre clothimpregnated with a 0.1 per cent solution of Chlorazol Fast Orange G(Journal Society Dyers and Colourists, 1938, page 269) and then dried byblowing hot air onto one side only, shows practically no differentialdyeing effect because this particular dyestuff has a good substantivityfor the staple fibre at the low temperature of impregnation. On theother hand, on impregnating with a 0.3 per cent solution of ChlorazolFast Orange AG (Journal Society Dyers and Colourists, 1938, page 270)and then drying by blowing with hot air on one side only, a very markeddifferential dyeing effect is obtained, because Chlorazol Fast Orange AGhas a negligible substantivity for viscose staple fibre at thetemperature of impregnation. Similarly, when, used in alike process, a,0.5 per cent solution of I ndigosol Blue 1330 (Journal Society Dyers andColourists, 1938, page 97) has low substantivity and therefore showslarge dyeing contrast, whilst a 0.5 per cent solution of Soledon JadeGreen (Journal Society Dyers and Colourists, 1927, page 100) shows nosubstantial contrast because it has a high substantivity for viscosestaple fibre at the temperature of impregnation.

It is thus evident that, when carrying out our invention, the compoundor compounds with which the fabric is impregnated must not have apronounced afiinity for or even chemical action on the material of thefabric, under the conditions of impregnation, but not necessarily underthe conditions of any subsequent treatment.

It is also desirable or even necessary, when carrying out the process ofthis invention, to take care that the current of air, especially if thisbe hot, be prevented from impinging on or surrounding the reverse sideof the fabric. Thus, an enclosed stenter, where the hot air cannot getaway from the material quickly, does not give anything like as gooddifferential effects as a completely open stenter in which the hot airblows on one side of the fabric only. v I

The process of our invention can beapplied to such textile fabrics asthose obtained for instance by weaving, knitting or felting, and thefabrics may be made of any suitable fibres, such for instance asregenerated cellulose or other rayons such as cellulose acetate, casein,Vinyon and nylon in either continuous or cut lengths, or of naturalfibres such as cotton and wool. Mixed fabrics may also be treated in asimilar manner.

The invention is illustrated'by the following examples in which thepercentages are by weight. In the dyebaths a liquor to yarn ratio of40:1 is used in each case.

Example 1 An aqueous impregnating solution is prepared by mixing 2.4lbs. of 40 per cent (commercial) formaldehyde with 3 gallons of a 2 percent aqueous cyanamide solution, adjusting the pH value of the solutionso obtained to 6.0 by means of aqueous caustic soda solution of 72 Tan,and dissolving in the solution 0.3 lb. of ammonium thiocyanate. lbs. ofa tubular knitted viscose yarn fabric are impregnated in a pad manglewith the resultant solution and squeezed till the fabric retains its ownWeight of solution. The fabric is then difierentially dried on a tubulardrier with air at 60 to 70 centigrade blow into the interior of thefabric, and the fabric is then heated for 3 minutes at 148 centigrade inorder to complete the condensation of the 'cyanamide and formaldehyde.The fabric is scoured for 10 minutes at 40 centigrade in an aqueoussolution containing 2 per cent of Lissapol LS and 1 per cent of 0.880ammonia. Lissapol is a registered trade-mark. It is then introduced intoa cold dyebath containing 2 per cent of A20 Geranine ZGS (Colour IndexNo. 31) and 2 per cent of formic acid, the temperature of the dyebath isthen raised in half an hour to 95 centigrade and dyeing continued atthis temperature for 45 minutes. The interior surface of the fabric onwhich the hot drying air impinged is uniformly dyed a heavier shade thanthe other side of the fabric.

Example 2 An aqueous impregnating solution is prepared by mixing 800cubic centimetres of 40 per cent formaldehyde with 10 litres of 2 percent aqueous cyanamide solution, adjusting the pH value to 6.0 withaqueous caustic soda solution of 72 TW., and dissolving in the solution67 grams of ammonium thiocyanate. 1 kilogram of a Woven cloth preparedfrom the viscose staple fibre as sold under the egistered trade-markFibre is steeped in the solution, squeezed till the cloth retains itsown Weight of solution and dried differentially by blowing hot air at 60to 70 centigrade on one side of the fabric only. The fabric is baked at140 centigrade for 3 minutes, scoured for 10 minutes at 40 centigrade inan aqueous 0.5 per cent soap solution and dyed as described in Example1.

Example 3 Three impregnating baths are prepared a follows:

(a) 10 litres of a 3 per cent aqueous dicyandiamide solution are mixedwith 1.6 litres of 40 per cent formaldehyde, the pH value of thesolution adjusted to 6.0 by means of aqueous caustic soda solution of 72Tw., and 200 grams of ammonium thiocyanate dissolved in the resultantsolution.

(b) 10 litres of a 2.5 per cent aqueous guanidine carbonate solution aremixed with 1 litre of 40 per cent formaldehyde and the pH value of thesolution adjusted to 7.0 by means of concentrated hydrochloric acid.

(0) 10 litres of water, 800 cubic centimetres of aqueous 70 per centethylene diamine and 4 litres of 40 per cent formaldehyde are mixedtogether and the pH value of the solution adjusted to 7.0 by means ofconcentrated hydrochloric acid.

Three batches each weighing 1 kilogram of a woven cloth prepared fromthe viscose staple fibre Fibre are steeped one in each of the abovebaths, squeezed till the cloths retain their own weight of solution anddried differentially by blowing hot air on one side only of the cloth.The cloths are heated for 15 minutes at 140 centigrade to effectcondensation and are scoured for 10 minutes at 40 centigrade with anaqueous 0.5 per cent soap solution. The cloths are then introduced intoa cold dyebath containing 2 per cent of Alizarine Brilliant Green G(Colour Index No. 1079) and 2 per cent of acetic acid. The temperatureof the dyebath is raised to centigrade in half an hour and dyeingcontinued at this temperature for 45 minutes. In each case the side ofthe fabric which the hot air strikes first is dyed a heavier shade thanthe other side.

Example 4 An aqueous impregnating solution is prepared by dissolving onepart of Chlorazol Fast Orange AG in parts of water. A fabric preparedfrom Fibre staple fibre is padded in this cold solution and squeezedevenly till it retains its own Weight of liquor. A hot air blast is thendirected on to one side of the fabric until the fabric is thoroughlydried. The side on which the hot air blast has impinged is found to bedyed to a considerably heavier shade than the other side of the fabric,

Example 5 An aqueous impregnating solution is prepared by dissolving 1part of Indigosol Blue 1130 in 100 parts of water. A cotton fabric ispadded in this cold solution and squeezed evenly till'it retains its ownweight of liquor. It is then dried by passage over a hot air blast. Thetrue shade is then developed by treating the fabric in an aqueous liquorcontaining 2 parts of sodium chloride. 1.85 parts of sulphuric acid of168 Tw., and onetenth-part of sodium nitrite per 100 parts of water.After treatment for 15 minutes at 25 centigrade the fabric is Washedfree from acid and finally treated in 40 times'its weight of a 0.1 percent solution of soap at 90 centigrade for 20 minutes. The side whichhas received the direct impact of the hot blast'is dyed more heavilythan the other side.

Example 6 A fabric prepared from Fibro staple-fibre is padded in a coldsuspension of 1 part Caledon Green RCS (Imperial Chemical IndustriesLimited) in 200 parts of water. It is then squeezed till it retains itsown weight of liquor and is dried by impinging a hot air blast on to oneside only of the fabric. The dried fabric is steeped for 10 minutes in asolution at 60 centigrade containing per 100 parts of water 2 parts ofcommon salt, 1.7 parts of caustic soda solution of 72 Tw. and 1 part ofsodium hydrosulphite. Following this treatment the fabric is squeezedand plunged into cold water. It is again squeezed, treated for 15minutes at 60 centigrade with 3 per cent of its weight of sodiumpercarbonate dissolved in 20 times its weight of water. Finally thefabric is treated at 90 centigrade for 15 minutes in a 0.1 per centsolution of soap.

Example 7 1 part of Indigosol Blue 130 powder is dissolved in 35 partsof water and 65 parts of Indus- .trial alcohol are added. A piece of 100per cent cellulose acetate rayon sateen is padded in this liquor,squeezed evenly and then a hot air draught is blown on to one side untilthe fabric is thoroughly dry. The fabric is then immersed for 15 minutesin a cold liquor containing 2 parts of sodium chloride, 1.85 parts ofsulphuric acid of 168 Tw. and one-tenth part of sodium nitrite, made upto 100 parts with water. The fabric is then rinsed in cold water andtreated in 40 times its weight of a 0.1 per cent solution of soap. Theside subjected to the hot air treatment is more heavily dyed than theother side of the fabric.

Example 8 A union fabric containing 50 parts of wool and 50 parts ofcasein fibre is padded in a cold 0.5 per cent aqueous solution ofChlorazol Dark Green PL conc. (Colour Index No. 583). It is thensqueezed and hot air is allowed to impinge on one side only of thefabric until the fabric is dry. This side is then found to be moreheavily dyed than the other side of the fabric.

Example 9 A wool fabric is padded in a suspension of 1 part of MonastralFast Blue BS (Journal Society Dyers and Colourists, 1936, vol. 52, page22) in 100 parts of cold water. The fabric is then squeezed and heatedon one side only by a draught of hot air until completely dry. Thepigment is then found to be more concentrated on this side than on theside not exposed to the draught.

Example 10 A wool fabric is padded in a solution of 1 part of AzoGeranine 2G3 and 2 parts of ammonium sulphate per 100 parts of water.After squeezing, the fabric is dried by applying a hot air draught toone side only of the fabric. This side is more heavily dyed than theside not so treated.

In this specification and in the appended claims, the word catalyst isused to designate such agents as will accelerate the formation of theresin.

What we claim is:

1. A process for the production of differential dyeing effects oncellulosic textile fabrics which comprises uniformly impregnating thesaid fabric with a liquid composition containing nitrogenousresin-forming compounds, evaporating the liquid medium from thethus-impregnated fabric so that the liquid is evaporated more rapidlyfrom predetermined portions than from the remaining portions of thefabric, heating the fabric to effect condensation f said nitrogenousresin-forming compoundsnand dyeing the said fabric.

2. A process as claimed in claim 1 wherein the nitrogenous resin-formingingredients are cyanamide and formaldehyde.

.3. A process for the production of differential dyeing effects oncellulosic textile fabrics which comprises uniformly impregnating thesaid fabric with a liquid composition containing cyanamide andformaldehyde and a catalyst evaporating the liquid medium fromthethus-impregnated fabric so that the liquid is evaporated more rapidlyfrom predetermined portions than from the remaining portions of thefabric, heating the fabric to effect condensation of the cyanamide andformaldehyde, and dyeing the said fabric.

4. A process as claimed in claim 1 wherein the liquid medium isevaporated more rapidly from one side of the fabricthan from the otherside of the fabric.

5. A process for the production of differential dyein effects oncellulosic textile fabrics which comprises uniforml impregnating thesaid fabric with a liquid composition containing cyanamide, formaldehydeand ammonium thiocyahate, evaporating the liquid medium from the thusimpregnated fabric so that the liquid is evaporated more rapidly frompredetermined portions than from the remaining portions of the fabric,heating the fabric to effect condensation of the cyanamide andformaldehyde, and dyeing the said fabric.

C. M. WHITTAKER. H. A. THOMAS.

C. C. WILCOCK C. P. TATTERSFIELD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,211,861 Platt Aug. 20, 19402,318,464 Cameron May 4, 1943 2,033,836 Lantz Mar. 10, 1936 2,093,651Windmer Sept. 21, 1937 2,123,152 Rivat July 5, 1938 2,039,176 LockerApr. 28, 1936 2,340,577 Bradshaw Feb. 1, 1944 FOREIGN PATENTS NumberCountry Date 462,724 British Mar. 11, 1937

